Update libffi to 3.1
Update gmp to 6.0.0a
Update nettle to 3.0
Update libgcrypt to 1.5.4
Update nettle to use 2.7.1 instead of 3.0

nettle 3.0 isn't supported by gnutls
Update protobuf-c to 1.0.1
Update gnutls to 3.2.17
Update bitlbee to 3.2.2
Merge branch 'develop' of github.com:SynoCommunity/spksrc into develop
Add changelog for btsync spk
More fixes for pkg-config files
Update glib to 2.38.2
Remove obsolete --disable-gtk in transmission
Fix lib dir in libffi
Update umurmur to 0.2.15